1. Field of the Invention (Technical Field)
The present invention relates to accentuating graphical elements on a housing, in particular to icons, alphanumeric characters, and logos located on a mobile handset housing.
2. Background Art
Mobile telephone handsets typically comprise a rigid housing enclosing a printed circuit board, the associated electronic and electro-acoustic components, and an antenna, through which radio frequency (RF) signals are transmitted and received. The telephone user interfaces with the circuitry and microprocessor of the telephone through a keypad located on the front outer surface of the housing. This keypad is often located on the same face of the housing as the microphone and speaker through which the user speaks and listens during communication. Keys on the keypad are pressed by the user to temporarily close an internal switch and send a signal to the microprocessor of the telephone where an appropriate routine processes the input and performs the desired function. Graphical elements, including alphanumeric characters and icons, are located on or adjacent the keys to guide the user in interfacing with the telephone. For example, the numbers 0-9 may be located on the keys, as well as letters of the alphabet, the pound and asterisk signs, and a variety of menu navigation symbols. A display above the keypad on the telephone housing often provides menus, messaging, and readouts of data input by the user. Further, the manufacturer of the telephone or the service provider may provide one or more logos on the housing to build brand awareness. Accordingly, it is important that the logo be prominently positioned to increase user perception. However, due to the physical space constraints on a mobile handset, the logo or logos may be of limited size and perceptibility. Also, the logos are merely printed on or attached to the housing, so are not visible in a darkened environment.
In order to enhance visibility of the alphanumeric characters or icons located on the keys of the keypad, lighting is often provided from behind the keypad and within the telephone housing to illuminate either the graphical elements on the keys or the keys themselves. Backlighting is typically provided from an array of light emitting diodes (LEDs) or an electroluminescent (EL) panel located directly behind the keypad. Each LED may be located behind a particular key or the array may be located generally behind the keypad to provide diffuse lighting. This type of backlighting illuminates the keypad material surrounding the graphics in the case where the graphics are more opaque than the keys of the keypad, for example, when the graphics are black and the keys are white. Alternatively the backlighting illuminates the graphics in the case where the keys are opaque in comparison to the graphics, for example, when the graphics are white and the keys are black. The LED array is powered from the power supply for the telephone electronics, which is typically a battery, and is illuminated upon activation of the telephone, such as when the user turns on the telephone, when a call is made, or when a call is answered.
The prior art method of placing graphics on the keys of a telephone limits the graphics configuration available to the telephone manufacturer to that on the keypad designed for its telephones. For example, only a very limited amount of information may be positioned on a typical key. Further, when graphics are located on the keypad, they are constantly being contacted by the user's fingertips when interfacing with the telephone potentially causing wear and fading of the graphics. This inhibits the user's ability to view the graphics and limits the useful life of the telephone. Also, when user interface graphics are located only on the keys, the keys must be made of a material than can be illuminated to enhance the visibility of the graphics.